Polymer composition

ABSTRACT

A composition may contain a first polymer, a second polymer, and a block copolymer. The first polymer may be polyactic acid, starch, polybutylene succinate, poly(butylene adipate-co-terephthalate), or a mixture thereof. The second polymer may be polybutadiene, high impact polystyrene, or a mixture thereof. The block copolymer may be a block copolymer of polylactic acid and polybutadiene. The composition may be prepared by a process that includes contacting the first polymer with the second polymer and the block copolymer. Articles may be prepared from the composition.

FIELD OF THE INVENTION

The invention pertains to a composition comprising a biopolymer such aspolylactic acid (PLA), and at least one second polymer.

BACKGROUND OF THE INVENTION

Polylactic acid (PLA) is a synthetic aliphatic polyester derived fromrenewal resources, such a corn, sugar beet and cassava, which canultimately be degraded under composting conditions.

Although attempts have been made to utilize PLA for various end-useapplications, PLA is known to be brittle and exhibit low toughness,which can result in low impact strength products or articles. Impactresistance of PLA can be modified by using existing polymeric impactmodifiers; however, currently available polymeric impact modifiersalways decrease transparency of PLA material. For example a liquidplasticizer can be used at high content (>15%) to improve impactresistance of PLA, however during the life time of the PLA blend, thereis migration of the plasticizer. Furthermore, it is no possible to useliquid plasticizer in crystalline PLA without avoidingre-crystallization that boosts plasticizer migration.

Impact modifiers such as rubber, poly(ethylene glycol) (PEG),acrylonitrile-butadiene-styrene copolymer (ABS) have been tested.Nevertheless, the immiscibility between these impact modifying additivesand the PLA matrix is a major drawback.

Commercially available BioStrength® 150 a methylmethacrylate-butadiene-styrene co-polymer (MBS) is one of the bestcurrently available impact modifiers for PLA; however haze of theresulting PLA material increases from 5, for pure PLA to 95 when 15% w/wof BioStrength® 150 is added. Another commercial product. BioStrength®280, an acrylic core shell impact modifier, is a less efficient impactmodifier, although the resulting PLA material is said to remaintransparent. Nevertheless, the present inventors observed that addition0115% w/w of BioStrength®280, produces a material with a haze of 44.

Plasticizers are additives that increase the fluidity of a material.Commonly used plasticizers, are tributyl citrate (TBC) and acetyltributyl citrate (ATBC). However, when 15% TBC or ATBC were mixed withPLA, the present inventors observed a plasticizer migration afterstorage for a few days at room temperature in summer time (25-30° C.),

In turn, Grinsted plasticizer is said not to migrate, however thepresent inventors observed whitening of PLA-containing Grinstedplasticizer during storage. Additionally differential scanningcalorimetry (DSC) showed beginning of crystallization on aged material,Therefore, it can be said that this material is not stable during longerperiod of time.

Other commonly used polymer modifiers are styrene block copolymers, suchas poly(styrene-butadiene-styrene), or SBS, Further studies performed bythe present inventors, showed that a blend of PLA with SBS exhibited atotal incompatibility even at a concentration as low as 10% w/w of SBS,

There is therefore a need to improve the compositions of the prior art.

SUMMARY OF THE INVENTION

A first aspect of the present invention provides a compositioncomprising:

-   -   at least one first polymer, selected from the group comprising        polylactic acid (PLA), starch, polybutylene succinate (PBS),        poly(butylene adipate-co-terephthalate) (PBAT) and mixtures        thereof;    -   at least one second polymer selected from polybutadiene (PB),        high impact polystyrene (HIPS), or mixtures thereof; and    -   at least one block copolymer of polylactic acid (PLA) and        polybutadiene (PB).

The present inventors have surprisingly found that a block copolymer ofPLA and PB was a good compatibilizer for a composition comprising abiopolymer such as polylactic acid (PLA), and another polymer such aspolybutadiene. In addition, the present inventors have shown thatcompositions according to the present invention have improved impactresistance.

A second aspect of the present invention encompasses a process forpreparing a composition according to the first aspect of the invention,said process comprising the steps of

-   contacting at least one first polymer, selected from the group    comprising polylactic acid (PLA), starch, polybutylene succinate    (PBS), poly(butylene adipate-co-terephthalate) (PBAT) and mixtures    thereof;-   with at least one second polymer selected from polybutadiene (PB),    high impact polystyrene (HIPS), or mixtures thereof; and-   and with at least one block copolymer of PLA and PB.

A third aspect of the invention encompasses an article comprising acomposition according to the first aspect of the invention, or formedusing a process according to the second aspect of the invention,

Preferred embodiments of the invention are disclosed in the detaileddescription and appended claims. In the following passages differentaspects of the invention are defined in more detail. Each aspect sodefined may be combined with any other aspect or aspects unless clearlyindicated to the contrary, In particular, any feature indicated as beingpreferred or advantageous may be combined with any other feature orfeatures indicated as being preferred or advantageous.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 represents a graph showing the DSC profile of the composition A1.according to an embodiment of the invention,

FIG. 2 represents a graph showing the DSC profile of the composition A2.

FIG. 3 shows a scanning electron microscopy (SEM) image of thecomposition A1 according to an embodiment of the invention.

FIG. 4 shows a scanning electron microscopy (SEM) image of thecomposition A2.

FIG. 5 shows a scanning electron microscopy (SEM) image of thecomposition A3.

DETAILED DESCRIPTION OF THE INVENTION

When describing the invention, the terms used are to be construed inaccordance with the following definitions, unless a context dictatesotherwise.

Unless otherwise defined, all terms used in disclosing the invention,including technical and scientific terms, have the meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. By means of further guidance, term definitions are included tobetter appreciate the teaching of the present invention.

In the following passages, different aspects of the invention aredefined in more detail, Each aspect so defined may be combined with anyother aspect or aspects unless clearly indicated to the contrary. Inparticular, any feature indicated as being preferred or advantageous maybe combined with any other feature or features indicated as beingpreferred or advantageous.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment of the present invention, Thus, appearances of the phrases“in one embodiment” or “in an embodiment” in various places throughoutthis specification are not necessarily all referring to the sameembodiment, but may, Furthermore, the particular features, structures orcharacteristics may be combined in any suitable manner, as would beapparent to a person skilled in the art from this disclosure, in one ormore embodiments. Furthermore, while some embodiments described hereininclude some but not other features included in other embodiments,combinations of features of different embodiments are meant to be withinthe scope of the invention, and form different embodiments, as would beunderstood by those in the art.

The terms “comprising”, “comprises” and “comprised of” as used hereinare synonymous with “including”, “includes” or “containing”, “contains”,and are inclusive or open-ended and do not exclude additional,non-recited members, elements or method steps. It will be appreciatedthat the terms “comprising”, “comprises” and “comprised of” as usedherein comprise the terms “consisting of”, “consists” and “consists of”.

As used in the specification and the appended claims, the singular forms“a”, “an,” and “the” include plural referents unless the context clearlydictates otherwise. By way of example, “a layer” means one layer or morethan one layer.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as is commonly understood by one of skill in theart. All publications referenced herein are incorporated by referencethereto.

The recitation of numerical ranges by endpoints includes all integernumbers and, where appropriate, fractions subsumed within that range(e.g. 1 to 5 can include 1, 2, 3, 4 when referring to, for example, anumber of elements, and can also include 1.5, 2, 2.75 and 3.80, whenreferring to, for example, measurements). The recitation of end pointsalso includes the end point values themselves (e.g. from 1.0 to 5.0includes both 1.0 and 5.0). Any numerical range recited herein isintended to include all sub-ranges subsumed therein.

The present invention provides a composition comprising:

-   -   at least one first polymer, selected from the group comprising        polylactic acid, starch, polybutylene succinate, poly(butylene        adipate-co-terephthalate) and mixtures thereof; preferably        wherein said at least one first polymer is polylactic acid;    -   at least one second polymer selected from polybutadiene, high        impact polystyrene, or mixtures thereof; preferably wherein said        at least one second polymer is polybutadiene and    -   at least one block copolymer of polylactic acid and        polybutadiene , also referred herein as PLA-PB block copolymer,

The present composition comprises at least one ^(.)first polymer,selected from the group comprising polylactic acid, starch, polybutylenesuccinate, poly(butylene adipate-co-terephthalate), and mixturesthereof.

The composition may comprise from 5% to 95% by weight, for example from10% to 90% by weight, for example from 20% to 80% by weight, .forexample from 30% to 70% by weight of said at least one first polymerbased on the total weight of the composition, for example.

In a preferred embodiment, said at least one first polymer is polylacticacid.

As used herein, the terms “polylactic acid” or “polylactide” or “PLA”are used interchangeably and refer to poly(lactic acid) polymerscomprising repeat units derived from lactic acid. Examples of suitablegrades of polylactic acid include but are not limited to Synterra® PLLA1010 from Synbra Technology by, NatureWorks® PLA polymer 6201D,NatureWorks PLA polymer 3251, and Futerro® PLA,

Polylactic acid suitable for the composition can be prepared accordingto any method known in the state of the art. The polylactic acid can beprepared by ring-opening polymerization of raw materials having requiredstructures selected from lactide, which is a cyclic dimer of lacticacid, glycolide, which is a cyclic dimer of glycolic acid, andcaprolactone and the like. Lactide includes L-lactide, which is a cyclicdimer of L-lactic acid, D-lactide, which is a cyclic dimer of D-lacticacid, meso-lactide, which is a cyclic dimer of D-lactic acid andL-lactic acid, and DL-lactide, which is a racemate of D-lactide andL-lactide, The PLA used in the present composition can be derived fromL-lactic acid, D-lactic acid, or meso-lactide, or a mixture thereof. Amixture of two or more polylactic acid polymers can be used.

Polylactic acid for use in the present composition can be preparedaccording to any known method such as the process described in documentsWO1998/002480. WO 2010/081887, FR2843390, U.S. Pat. No. 5,053,522, U.S.Pat. No. 5,053,485 or U.S. Pat. No. 5,117,008.

In an embodiment, the polylactic acid can be obtained by polymerizinglactide, in the presence of a suitable catalyst, and optionally in thepresence of a compound of formula (I), acting as a co-initiator andtransfer agent of the polymerization,

R¹—OH   (I)

wherein R¹ is selected from the group consisting of Cu₁₋₂₀alkyl,C₆₋₃₀aryl, and C₆₋₃₀arylC₁₋₂₀alkyl optionally substituted by one or moresubstituents selected from the group consisting of halogen, hydroxyl,and C₁₋₈alkyl. Preferably, R¹ is selected from C₃₋₁₂alkyl, C₅₋₁₀aryl,and C₆₋₁₀arylC₃₋₁₂alkyl, optionally substituted by one or moresubstituents, each independently selected from the group consisting ofhalogen, hydroxyl, and C₁₋₆alkyl; preferably, R¹ is selected fromC₃₋₁₂alkyl, C₆₋₁₀aryl, and C₆₋₁₀arylC₃₋₁₂alkyl, optionally substitutedby one or more substituents, each independently selected from the groupconsisting of halogen, hydroxyl and C₁₋₄alkyl. The alcohol can be apolyol such as diol, triol or higher functionality polyhydric alcohol.The alcohol may be derived from biomass such as for instance glycerol orpropanediol or any other sugar-based alcohol such as for exampleerythritol. The alcohol can be used alone or in combination with anotheralcohol. In an embodiment, non-limiting examples of initiators include1-octanol, isopropanol, propanediol, trimethylolpropane, 2-butanol,3-buten-2-ol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol,1,7-heptanediol, benzyl alcohol, 4-brornopheno1,1,4-benzenedimethanol,and (4-trifluorornethyl)benzyl alcohol; preferably, said compound offormula (I) is selected from 1-octanol, isopropanol, and 1,4-butanediol.

The polylactic acid structure can be of the following types in terms ofchain termination:

-   R—OH and R—COOH, with R being the polylactic acid chain, obtainable    when using monoalcohol as co-initiator,-   HO—R—OH and HOOC—R—COOH obtainable when using dial as co-initiator,-   or multiple OH (e.g. 5), obtainable when using triol or higher    functionality polyhydric alcohol as co-initiator,

The polylactic acid for use in the present composition also includescopolymers of lactic acid. For instance, copolymers of lactic acid andtrimethylene carbonate according to EP 11167138 and copolymers of lacticacid and urethanes according to WO 2008/037772 and POT applicationnumber PCT/EP2011/057988.

The polylactic acid for use in the present composition may comprise theproduct of polymerization reaction of a racemic mixture of L-lactidesand D-lactides, also known as poly-DL-lactide . The polylactic acid foruse in the present composition may comprise the product ofpolymerization reaction of mainly D-lactides (or D,D-lactides), alsoknown as poly-D-lactide (PDLA). In an embodiment, the polylactic acidfor use in the present composition may comprise the product ofpolymerization reaction of mainly L-lactides (or L,L-lactides), alsoknown as poly-L-lactide (PLLA). Other suitable polylactic acid can becopolymers of PLLA with some D lactic acid units. PLLA-PDLAstereocomplexes, as described for example in WO 2010/097463, can also beused. The polylactic acid for use in the present composition maycomprise the product of polymerization reaction of meso-lactides.

In an embodiment, the PLLA or the PDLA respectively have an opticalpurity (called isomeric purity) of the L or D isomer, which is higherthan 92% of the PLA, preferably higher than 95 w % by weight. An opticalpurity from at least 98% by weight is more preferred.

Optical purity can be measured by different techniques, such as NMR,polarirnetry or by enzymatic method or GCMS. Preferably, optical purityis measured by enzymatic method and/or NMR, as described for hereinbelow. Enzymatic method: The stereochemical purity of the PLLA or of thePDLA can be determined from the respective content of L-mer or of D-mer.The terms “content of D-mer” and “content of L-mer” refer respectivelyto the monomer units of type D and of type L that occur in polylactide,using the enzymatic method. The principle of the method is as follows:The L-lactate and D-lactate ions are oxidized to pyruvate respectivelyby the enzymes L-lactate dehydrogenase and D-lactate dehydrogenase usingnicotinamide-adenine dinucleotide (NAD) as coenzyme. To force thereaction in the direction of formation of pyruvate, it is necessary totrap this compound by reaction with hydrazine. The increase in opticaldensity at 340 nm is proportional to the amount of L-lactate or ofD-lactate present in the sample. The samples of PLA can be prepared bymixing 25 ml of sodium hydroxide (1 mol/L) with 0.6 g of PLA. Thesolution was boiled for 8 h and then cooled. The solution was thenadjusted to neutral pH by adding hydrochloric acid (1 mol/L), thendeionized water was added in a sufficient amount to give 200 ml, Thesamples were then analyzed on a Vital Scientific Selectra Junioranalyzer using, for L-mer determination of poly-L-lactide acid, the boxtitled “L-lactic acid 5260” marketed by the company Scil and for D-merdetermination of poly-D-lactide acid, the box titled “L-lactic acid5240” marketed by the company Scil. During the analysis, a reactiveblank and calibration using the calibrant “Scil 5460” are used. Thepresence of insertion and racemization defects can also be determined bycarbon-13 nuclear magnetic resonance (NMR) (Avance, 500 MHz, 10 mm SELXprobe). The samples can be prepared from 250 mg of PLA dissolved in 2.5to 3 ml of CDCl₃.

In an embodiment, the PLLA for use in the composition thus comprises acontent of D isomer lower than 8% by weight, preferably lower than 5% byweight, more preferably lower or equal to 2% by weight of the PLLA, forexamples a content of L isomer lower than 1% by weight of the PLLA, forexamples a content of L isomer lower than 0.5% by weight of the PLLA. Byanalogy, the PDLA comprises a content of L isomer lower than 8% byweight, preferably lower than 5% by weight, more preferably lower orequal to 2% by weight of the PDLA, for examples a content of L isomerlower than 1% by weight of the PDLA, for examples a content of L isomerlower than 0.5% by weight of the PDLA.

Polylactic acid (PLLA or PDLA) preferably has a weight average molecularweight (Mw) ranging between 30,000 and 500,000 g/mol, more preferablybetween 50,000 and 400,000 g/mol, even more preferably between 70,000and 300,000 g/mol. The weight average molecular weight can be measuredby chromatography by gel permeation compared to a standard polystyrenein chloroform at 30° C. Measurement of the molecular masses may beperformed using a liquid chromatograph WATERS 610. Firstly, a polymersolution is prepared in chloroform (1 mg polymer/ml), Then, 100 μl ofthis solution is taken and injected, through a filter (with pores of 0.2μm diameter, on the chromatograph column at 25° C. Molecular masses aredetermined from the retention time in the column, translated in massequivalent using a universal calibration law based on polystyrenestandards. For example, ASTM practice D3016-97(2010) may be used. In anembodiment, the ratio of the weight average molecular weight (Mw) to thenumber average molecular weight (Mn) is generally from 1.0 to 5.0.

In an embodiment, the polylactic acid may have a density of from 1.228g/cm³ to 1.269 g/cm³, for example from 1,230 g/cm³ to 1,260 g/cm³, forexample from 1.235 g/cm³ to 1.255 g/cm³ (as determined in accordancewith ASTM D792).

In an embodiment, the polylactic acid may exhibit a crystalline melttemperature (Tc) of from 140° C. to 190° C., for example from 145° C to185° C., for example from 160° C. to 180° C. (as determined inaccordance with ASTM D3418).

In an embodiment, the polylactic acid may exhibit a glass transitiontemperature (Tg) of from 45° C. to 85° C., for example from 50° C. to80° C., for example from 50° C. to 70° C. (as determined in accordancewith ASTM D3417).

In an embodiment, the polylactic acid may exhibit a tensile yieldstrength of from 4000 psi to 25000 psi, for example from 5000 psi to10000 psi, for example from 5500 psi to 8500 psi (as determined inaccordance with ASTM D638).

In an embodiment, the polylactic acid may exhibit a tensile elongationof from 0.5% to 10%, for example from 1.0% to 8%, for example from 1.50%to 6% (as determined in accordance with ASTM D638).

In an embodiment, the polylactic acid may exhibit a tensile modulusstrength of from 3100 MPa to 4000 MPa (as determined in accordance withISO-527).

composition may include from 5% to 95% by weight, for example from 10%to 90% by weight, for example from 20% to 80% by weight, for examplefrom 30% to 70% by weight of polylactic acid based on the total weightof the composition,

In an embodiment, the at least one first polymer is starch, The starchthat can he utilized in the composition includes, for example, potatostarch. COM starch, wheat starch, rice starch, amaranth, tapioca starch,and the like. The term starch generally applies to a white, granular orpowdery, odourless, tasteless, complex carbohydrate, preferably withformula (C₆H₁₀O₅)x, which can be abundant in the seeds of cereal plantsand in bulbs and tubers. In an embodiment, starch refers to a polymer ofglucose found as a reserve in most plants. Starch preferably comprisesa-glucosidic bonds, which can cause helix-shaped molecules. Preferably,starch comprises molecules having at least two kinds of structures: (i)amylase (structure 1), wherein the C₆H₁₀O₅ groups can be (linked mainlyα(1-4) bonds) arranged in a continuous but curled chain somewhat like acoil of rope; and (ii) amylopectin (structure 2), wherein considerableside-branching of the molecule can Occurs.

In some embodiments, the term starch also comprises, starch ester,starch ether, starch succinate, and starch xanthate. Starch esters aremodified starch comprising ester groups like acetylated starch andstarch monophosphate. For example, potato starch is a natural starchphosphate ester, Starch ethers are modified starch comprising ethergroups such as hydroxypropyl-starch, cationic starch and carboxymethylstarch, Starch succinates comprise anionic starch esterified bysuccinate groups. Starch xanthates are starch esterified by xanthategroups. Starch derivatives, such as through hydrolysis to yield forexample dextrins (for example, maltodextrin), alone or in combinationwith starches also can be utilized according to the invention,

In an embodiment, the at least one first polymer is polybutylenesuccinate. As used herein, the terms “PBS” or “polybutylene succinate”are used interchangeably and refer to polybutylene succinate polymers,Suitable polybutylene succinate can be obtained by polycondensationreactions of glycols, such as 1,4-butanediol, with a dicarboxylic acidor an acid anhydride thereof, such as succinic acid, A polybutylenesuccinate polymer may either be a linear polymer or a long-chainbranched polymer. A long-chain branched polybutylene succinate polymercan be prepared by using an additional polyfunctional component selectedfrom the group consisting of trifunctional or tetrafunctional polyols,oxycarboxylic acids, and polybasic carboxylic acids. Polybutylenesuccinate polymers are known in the art and are described, for example,in EP 0 569 153 to Showa Highpolymer Co., Ltd., Tokyo, Japan.Non-limiting exemplary polymer is a polybutylene succinate homopolymersold under tradename Bionelle 1000™ available from Showa HighpolyrnerCo., Ltd,

In an embodiment, the at least one first polymer is poly(butyleneadipate-co-terephthalate). As used herein, the terms “PBAT” or“poly(butylene adipate-co-terephthalate)” are used interchangeably andrefer to polymers encompassing random copolymer of butylene adipate andterephthalate. Poly(butylene adipate-co-terephthalate) suitable for thepresent composition can be prepared according to any method known in thestate of the art, For example, poly(butylene adipate-co-terephthalate)can be prepared by polycondensation between 1,4-butanediol and a mixtureof adipic acid and terephthalic acids. Non-limiting commercial examplesinclude Ecoflex® (BASF); Oligo-Bi® (Novamont); EnPOL™ G8060 and EnPOL™8000 by Ire Chemical Ltd of Seoul.

The present composition also comprises at least one second polymerselected from polybutadiene (PB), high impact polystyrene (HIPS), ormixtures thereof.

The composition may comprise from 5% to 95% by weight, for example from10%to 90% by weight, for example from 20% to 80% by weight, for examplefrom 30% to 70% by weight of said at least one second polymer based onthe total weight of the composition.

In a preferred embodiment, the at least one second polymer ispolybutadiene. As used herein, the terms “PB” or “polybutadiene” areused interchangeably. Polybutadiene suitable for the present compositioncan be prepared according to any method known in the state of the art.Suitable polybutadiene includes polymer formed from the polymerizationof 1,3-butadiene, The micro-structure of the polybutadiene can be any ofthe conventional types containing various amounts of 1,2-vinyl, 1,4-cisand 1,4-trans levels. Non-limiting suitable examples of polybutadieneinclude polybutadiene of essentially linear structure.

Advantageously the weight average molecular weight (Mw) of thepolybutadiene can range from 100,000 to 500,000 and preferably from280,000 to 360,000 g/mol. Advantageously the polydispersity index of thepolybutadiene can range from 2.1 to 2.5 and preferably from 2.1 to 2.3.Polybutadiene molecular-weights can be measured by the conventionalsize-exclusion chromatography techniques. They are here expressed in PSequivalents, i.e. using iso-molecular PS samples as calibrationstandards.

Particularly suitable polybutadiene can have a solution viscosity (SV),measured at 5.43% weight in toluene or styrene, of 50 to 1000centipoises, preferably from 100 to 500 centipoises and more preferablyfrom 120 to 250 centipoises (measured according to IC-5a). Particularlysuitable polybutadiene can have a Mooney viscosity (ML4+1, 100° C.) of 5to 120 , preferably from 10 to 100 and more preferably from 30 to 60 ME(measured according to ASTM D 1646). Particularly suitable polybutadienecan have a SV-to-Mooney viscosity ratio of at least 2.8, and morepreferably above 3,3.

Particularly suitable polybutadiene can have a cis content of at least90%, for example at least 95%, wherein the cis content is measured byinfrared spectroscopy or nuclear magnetic resonance as known to one ofordinary skill in the art.

Examples of polybutadiene suitable for use in this composition includewithout limitation BUNA CB 728 T or Buna CB 1414, or Buna CB 1415butadiene elastomers, which are high cis polybutadiene elastomerscommercially available from LANXESS Deutschland GmbH.

Suitable polybutadiene include also functionalized polybutadiene.Suitable functionalization include b are not limited to hydroxyl, epoxy,maleic anhydride, silane or tailor made structures.

In an embodiment, the at least one second polymer is high impactpolystyrene (HIPS). As used herein, the terms “HIPS” or “high impactpolystyrene” are used interchangeably. The process for making HIPS iswell known to those skilled in the art. For example, the process maycomprise polymerizing styrene monomer in the presence of dissolvedrubber. Polymerization of styrene, and optionally a comonomer, may beinitiated by heating and/or by an initiator, by way of example a radicalinitiator, The rubber may be “dissolved” in the styrene monomer. Theusual rubber types utilized in the manufacture of HIPS includepolybutadiene (PB), styrene-butadiene rubber (SBR), andstyrene-butadiene-styrene rubber (SBS), Polystyrene may be initiallyformed from the styrene monomer within the homogeneous rubber solutionin styrene, In HIPS, a part of the styrene may be replaced byunsaturated monomers copolymerizable with styrene such as othermonovinylaromatic monomers, alkyl esters of acrylic or methacrylic acidand acrylonitrile. Non-limiting examples of suitable processes forpreparing HIPS are described in US20101240832, incorporated herein byreference.

The present composition also comprises at least one block copolymer ofPLA and PB. The composition may comprise from 1% to 90% by weight, forexample from 4% to about 50% by weight, for example from 10% to 40% byweight, for example from 10% to 30% by weight of said block copolymerbased on the total weight of the composition, for example.

Suitable block copolymer comprises polymer comprising multiplesequences, or blocks, of the same monomer alternating in series withdifferent monomer blocks; these blocks are covalently bound to eachother. Block copolymers are normally prepared by controlledpolymerization of one monomer, followed by chain extension with adifferent monomer, Block copolymers are classified based on the numberof blocks they contain and how the blocks are arranged. For example,block copolymers with two blocks are called diblocks; those with threeblocks are triblocks; and those with more than three are genericallycalled multiblocks. Classifications by arrangement include the linear,or end-to-end, arrangement and the star arrangement, in which onepolymer is the base for multiple branches,

In an embodiment, said block copolymer is selected from PLA-PB diblockcopolymer, PLA-PB-PLA triblock copolymer, PLA-PB multiblock copolymer,PLA-PB star copolymers,

PLA-PB comb copolymers. PLA-PB gradient containing block copolymers, andother copolymers having a blocky structure, which will be known by thoseskilled in the art, Preferable diblock and triblock copolymers includePLA-PB and PLA-PB-PLA block copolymers. An example of a gradientcontaining block copolymer is when the monomer or monomers used from onesegment are allowed to further react as a minor component in the nextsequential segment. For example, if the monomer mix used for the 1stblock (A block) of an AB diblock copolymer is polymerized to only 80%conversion, then the remaining 20% of the unreacted monomer is allowedto react with the new monomers added for the B block segment the resultis an AB diblock copolymer in which the B segment contains a gradient ofthe A segment composition. The term “comb copolymer,” as used herein,describes a type of graft copolymer, wherein the polymeric backbone ofthe graft copolymer is linear, or essentially linear and is made of onepolymer A, and each side chain (graft segment) of the graft copolymer isformed by a polymer B that is grafted to the polymer A backbone. Usedherein, the terms “comb copolymer” and “graft copolymer” have the samemeaning.

In an embodiment, the block copolymer is produced by combining a lactideand a polybutadiene, preferably a hydroxy functionalized polybutadiene,In one or more embodiments, the block copolymer is produced by meltblending a lactide and a hydroxy functionalized polybutadiene. Suchprocesses may utilize catalysts for polylactic acid formation, such astin compounds (e.g., tin octylate), titanium compounds (e.g.,tetraisopropyl titanate), zirconium compounds (e.g., zirconiumisopropoxide), antimony compounds (e.g., antimony trioxide) orcombinations thereof, for example.

Among the hydroxyl-terminated polybutadienes that are useful forpreparing the block copolymers are those possessing a number averagemolecular weight (Mn) of at least 1000 g/mol, for example at least 5000g/mol, preferably at least 10000 g/mol, for example at least 20000g/mol, for example at least 30000 g/mol, for example from 1000 to 40000g/mol, for example from 1000 to 35000 g/mol, for example from 1000 to25000 g/mol, for example from 1000 to 20000 g/mol, for example From 1000to 15000 g/mol, and advantageously from 1000 to 10000 g/mol.

Among the hydroxyl-terminated polybutadienes that are useful forpreparing the block copolymers are those possessing a hydroxyl groupcontent of from 0.10 to 3.0 Mmol/g.

Hydroxyl-terminated polybutadienes of the above-described type,averaging more than one predominantly primary hydroxyl group permolecule, e.g., averaging from 1.5 to 3 or more primary hydroxyl groupsper molecule, can be suitably employed herein. Branchedhydroxyl-terminated polybutadienes can possess an average of at least1.90, and advantageously from 1.95 up to 2.8, hydroxyl groups permolecule, the hydroxyl groups being predominantly in terminal positionson the main, i.e., the terminal hydroxyl groups of the polymer, arebonded to carbon atoms adjacent to double bonded carbon atoms.

The hydroxyl-terminated polybutadiene may have a vinyl content of atleast 15%, Herein a vinyl content of at least 10% refers tohydroxyl-terminated polybutadiene wherein at least 15% of the materialhas terminal double bonds.

The useful hydroxyl-terminated polybutadienes herein can alsoincorporate one or more other copolymerizable monomers that can conferparticularly desirable properties upon the copolymers herein and thecompositions prepared therewith. Included among the copolymerizablemonomers are mono-olefins and dienes such as ethylene, propylene,1-butene, isoprene, chloroprene, 2,3 -methyl- 1,3 -butadiene,1,4-pentadiene, etc., and, ethylenically unsaturated monomers such asacrylonitrile, methacrylonitrile, methylstyrene, methyl acrylate, methylmethacrylate, vinyl acetate, etc. Alternatively or in addition thereto,the hydroxyl-terminated polybutadienes can be reacted with one or moreother monomers to provide hydroxyl-terminated block copolymers. Suchmonomers include 1,2-epoxides such as ethylene oxide and propylene oxidewhich will provide polyether segments, e-caprolactone which will providepolyester segments, and the like.

Hydroxyl-terminated polybutadienes possessing these characteristics arecommercially available from several sources and are thereforeconveniently employed herein.

Examples of suitable hydroxyl-terminated polybutadiene include hut arenot limited to Krasol® LBH 10000, Krasol® LBH 2000, Krasol® LBH 3000 andKrasol® LBH 5000, Krasol® LBH-P 2000, Krasol® LBH-P 3000, Krasol® LBH-P5000, Poly Bd® R45HTLO, Poly Bd® R2OLM commercially available from HSCCray Valley Corp., as well as the epoxidized hydroxyl-terminatedpolybutadiene such as Poly bd® 605 and Poly bd® 600 commerciallyavailable from HSC Cray Valley Corp.

In an embodiment, said block copolymer comprises at least 10% by weightof hydroxyl functionalized polybutadiene based on the total weight ofthe block copolymer. In an embodiment, said block copolymer comprisesfrom 10% to 90% by weight of hydroxyl functionalized polybutadiene basedon the total weight of the block copolymer.

The present invention is directed towards use of such block copolymersas additives to compatibilize the first polymer with the second polymer.

In some embodiments, the composition comprises from 30 to 48% by weightof said first polymer, from 30 to 48% by weight of said second polymer,and from 4 to 40% by weight of said block copolymer, based on the totalweight of the composition.

In some embodiments, the composition comprises from 30 to 48% by weightof PLA, from 30 to 48% by weight of PB, and from 4 to 40% by weight ofblock copolymer, based on the total weight of the composition.

The present invention also encompasses a process for preparing acomposition comprising the steps of

-   contacting at least one first polymer, selected from the group    comprising polylactic acid , starch, polybutylene succinate,    poly(butylene adipate-co-terephthalate) and mixtures thereof;-   with at least one second polymer selected from polybutadiene, high    impact polystyrene , or mixtures thereof; and-   and with at least one block copolymer of polylactic acid and    polybutadiene.

Any process known in the art can be applied for preparing a compositionas presently described.

In some embodiments, said contacting step comprises melt blending thefirst polymer, the second polymer and the block copolymer, in a singlestep. The blending may occur by introducing the block copolymer, thefirst polymer, and the second polymer, into a system capable ofcombining and melting the components to initiate chemical and physicalinteractions between the block copolymer and the first and secondpolymers components. For example, the blending may be accomplished byintroducing the first and second polymers, and the block copolymer intoa batch mixer, continuous mixer, single screw extruder or twin screwextruder, for example, to form a homogeneous mixture or solution whileproviding temperature conditions so as to melt the blend components andinitiate chemical and physical interactions between the block copolymerand the first and second polymers components as described above, therebyproducing a compatibilized first and second polymers blend.

In another embodiment, contacting of the above-mentioned components maygenerally occur in a two-step process. In a first step, the firstpolymer and the block copolymer, may be melt blended. Subsequently, in asecond step, the second polymer may be introduced and melt blended withthe first polymer blend.

In an embodiment, the composition is prepared by extrusion. In anembodiment, the composition is extruded at a temperature of at least 90°C., for example at least 95° C., for example at least 100° C., forexample ranging from 100° C. to 230° C. More preferably, the compositionis extruded at a temperature ranging from 100° C. to 200° C.

In an embodiment, any of the previously described compatibilizedcompositions may further comprise additives to impart desired physicalproperties, such as printability, increased gloss, or a reduced blockingtendency. Examples of additives may include, without limitation,stabilizers, ultra-violet screening agents, oxidants, anti-oxidants,antistatic agents, ultraviolet light absorbents, fire retardants,processing oils, mold release agents, coloring agents, pigments/dyes,fillers or combinations thereof, for example. These additives may beincluded in amounts effective to impart desired properties.

In an embodiment, the compositions and blends thereof may be formed intoa wide variety of articles such as films, pipes, fibers (e.g., dyeablefibers), rods, containers, bags, packaging materials, and adhesives(e.g., hot melt adhesives) for example, by polymer processing techniquesknown to one of skill in the ad, such as forming operations includingfilm, sheet, pipe and fiber extrusion and co-extrusion as well as blowmolding, injection molding, rotary molding, and thermoforming, forexample. Films include blown, oriented or cast films formed by extrusionor co-extrusion or by lamination useful as shrink film, cling film,stretch film, sealing films, oriented films, snack packaging, heavy dutybags, grocery sacks, baked and frozen food packaging, medical packaging,industrial liners, and membranes, for example, in food-contact andnon-food contact application. Fibers include slit-films, monofilaments,melt spinning, solution spinning and melt blown fiber operations for usein woven or non-woven form to make sacks, bags, rope, twine, carpetbacking, carpet yarns, filters, diaper fabrics, medical garments andgeotextiles, for example, Extruded articles include medical tubing, wireand cable coatings, hot melt adhesives, sheets, such as thermoformedsheets (including profiles and plastic corrugated cardboard),geornembranes and pond liners, for example, Molded articles includesingle and multilayered constructions in the form of bottles, tanks,large hollow articles, rigid food containers and toys, for example.

In another embodiment, the cornpatibilized blend may be utilized as acompatibilizer to a second polymeric blend comprising a second firstpolymer and a second polymer to compatibilize the second blend. Thepresent invention can be further illustrated by the following examples,although it will be understood that these examples are included merelyfor purposes of illustration and are not intended to limit the scope ofthe invention unless otherwise specifically indicated.

EXAMPLES

Unless otherwise indicated, all parts and all percentages in thefollowing examples, as well as throughout the specification, are partsby weight or percentages by weight respectively.

Example 1 Preparation of Poly(lactide-b-butadiene-b-lactide TriblockCopolymer (Scheme 1)

Hydroxy terminated polybutadiene (Krasol®LBH10000 from HSC Cray ValleyCorp) was reacted with L-lactide in the presence of a catalyst toprepare the triblock copolymer. Krasol®LBH10000 from HSC Cray ValleyCorp, had the following properties: Microstructure: 1,2-(vinyl): about65 wt %, 1,4-cis: about 18 wt %; 1,4-trans: about 17 wt %; Content of OHgroups 0.16-0.22 (Mmol/g), Hydroxyl number 8.9-12.4 Mg KOH/g,

Viscosity Brookfield 20-50 Pa·s at 50° C. Density: about 0.9 g/cm³ at20° C.; Molecular weight (Mn): 9000-11000 g/mol, Polydispersity Index(Mw/Mn): 1.1. Purified L-Lactide from Futerro optical purity above 99.5%was used.

Hydroxy terminated polybutadiene (7.78 g) and L-lactide (8.0 g) wereheated to 185 ° C. under N₂ until a clear mixture was obtained. Sn(Oct)₂(112 mg) was added. Polymerization was carried out for 30 min and theproduct (copolymer 6) was precipitated in ethanol.

The same experiment was repeated with different concentrations ofhydroxyl terminated polybutadiene, and the modulus and tensileproperties of the copolymers were measured as described in ISO 527-1BA.The results are shown in Tables 1 and 2, and compared with the modulusand tensile properties measure for PLA (PLLA (NatureWorks® PLA polymer6201D).

TABLE 1 Modulus on PLA-PB-PLA copolymer (tensile −20 mm/min - 100%/min)at 23° C. PB HO-PB-OH Mn quantity (Mn) Conversion theoretic Haze ModulusExample % g · mol⁻¹ % g · mol⁻¹ % Mpa PLA6201 0 <10 3260 Copolymer 1 1410.000 92 72.100 <10 2031 Copolymer 2 19 10.000 91 52.600 <10 1637Copolymer 3 23 10.000 94 43.500 <10 848 Copolymer 4 26 10.000 91 38.500<10 787 Copolymer 5 32 10.000 95 31.500 <10 249 Copolymer 6 52 10.000 9519.250 <10 20

TABLE 2 Elongation at break on PLA-PB-PLA copolymer (tensile 20 mm/min -100%/min) at 23° C. PB Mn yield Break quantity HO-PB-OH Conversiontheoretic Tensile Stress Tensile Stress Example % g · mol⁻¹ % g · mol⁻¹Mpa % Mpa % PLA6201 0 70.2 2.3 55.7 6.8 Copolymer 1 14 10.000 92 72.10052.9 2.9 17.0 7.2 Copolymer 2 19 10.000 91 52.600 35.0 2.5 13.0 23.0Copolymer 5 32 10.000 95 31.500 12.7 2.5 11.5 25.7

Example 2

A composition according to an embodiment was prepared by blending 40% byweight of PLLA with 40% by weight of polybutadiene and 20% by weight ofcopolymer 6 prepared as described in example 1.

The composition was melt blended in counter-rotating twin screwextruder, at 200° C., 100 rpm, 5 bar, and a residence time of 2 min.

The PLLA used was Synterra® PLLA 1010 from Synbra Technology by, withthe following characteristics: a melt flow rate of 22 (±5) g/600 s (ISO1133 (190″C/2.16kg), a density of 125 g/cm³ (ISO 1183), a D-isomercontent lower than 1%, a melting temperature of 175-180° C. (DSC:ISO11357) and a glass transition temperature of 55-60° C. (DSC:ISO 11357).

The polybutadiene used was high cis polybutadiene BUNA CB 728 T fromLANXESS Deutschland GmbH, haying a Mooney viscosity of 44 ME (ISO289/ASTM D 1646), a solution viscosity (5.43% in toluene) of 160 mPa·s(ISO 3105 (543% in toluene), and a cis 1,4 content of 96% by weight,

Example 3

A composition A1 according to an embodiment of the invention wasprepared by blending 40% by weight of PLLA (Synterra® PLLA 2010 fromSynbra technology b.v) with 40% by weight of PLLA-PB-PLLA blockcopolymer 6 prepared in example 1, and with 20% by weight ofpolybutadiene (PB) (BUNA CB 728 T). The physical properties of Synterra®PLLA 2010 are shown in Table 3.

TABLE 3 PHYSICAL PROPERTIES TEST METHOD UNITS SPECIFICATION Appearanceround pellets Color Off white (crystallized) Melt Flow Rate ISO 1133g/600 s 4 (+−2) (190° C./2.16 kg) Polymer Density ISO 1183 g/cm³ 1.25Moisture content <400 ppm Residual Monomer % <0.5 D-Isomer % <1  Melting temperature DSC:ISO 11357 ° C. 175-180 Glass Transition DSC:ISO11357 ° C. 55-60 temperature

PLLA pellets were dried in a vacuum oven for 1 h at 110° C.

The composition A1 was melt blended in a (Haake) counter-rotating twinscrew mini-extruder, at 5 bars, 200° C., 100 rpm and a residence time of3 min for 5 passes.

A comparative composition A2 was prepared by blending 80% by weight ofPLLA (Synterra® PLLA 2010 from Synbra technology b.v) with 20% by weightof polybutadiene (BUNA CB 728 T).

The composition A2 was melt blended in a (Haake) counter-rotating twinscrew mini-extruder, at 200° C., 100 rpm and a residence time of 5 min.

Thermal properties of the composition were analyzed with Perkin-ElmerPyris Diamond differential scanning calorimeter (DSC) calibrated withindium as standard. The specimens were heated from 25 to 240° C. at arate of 20° C./min, under N₂, followed by an isothermal at 240° C. for3min, and a subsequent cooling scan to 25″C at rate of 20°C./min. Andthen were reheated to 240° C. at 20°C./min. Glass transition temperature(Tg), melting temperature (Tm) and the enthalpy of melting (ΔHm) weremeasured. The DSC thermogram of composition A1 is presented in FIG. 1.The DSC thermogram of composition A2 is presented in FIG. 2.

A comparative composition A3 was prepared by blending 60% by weight ofPLLA (Synterra® PLLA 2010 from Synbra technology b.v) with 40% by weightof polybutadiene (BUNA CB 728 T).

The composition was melt blended in Brabender co-rotating twin screwextruder, at 200° C., 100 rpm, 5 bar, and a residence time of 2 min.

Mechanical properties of the compositions were investigated by lzodimpact tester. Un-notched Izod impact was measured at 23° C. accordingto IS0180. Unnotched test specimen 9.99mm×4.21mm (section 42.1 mm²) isheld as a vertical cantilevered beam and is impacted at 3.5m/s by aswinging pendulum (5.5 J).

The results are shown in Table 4.

TABLE 4 Compositions Un-notched Izod (kJ/m²) Composition A1 51.4 ± 0.2Composition A2 21.4 ± 6.2 Composition A3  3.1 ± 2.5

An exceptional impact has been obtained in the composition Al with anUn-notched lzod measured at 51.4 kJ/m².

The compositions were further analyzed by Scanning backscatteredElectron Microscopy, The sample preparation was as follows: A test piecewas prepared with the composition; a 0.1 to 1 mm² surface was milled inthe test piece with a diamond bur. The surface was then out using amicrotome (0.35 microns/slice) using a diamond knife. The microtomecutting was performed at room temperature. The sample was then exposedto osmium tetraoxide (99.8% 0s04_(;) Aldrich) for 48 hours. The samplewas allowed to rest for 48 hours. The scanning surface was cut againwith a microtome at room temperature using a diamond knife.

FIG. 3 shows a scanning electron microscopy (SEM) image of thecomposition A1.

FIG. 4 shows a scanning electron microscopy (SEM) image of thecomposition A2.

FIG. 5 shows a scanning electron microscopy (SEM) image of thecomposition A3.

These results show that the presence of the PLA-PB-PLA copolymer incomposition A1 drastically improves the compatibility of the PLA and PBmaterials.

FIG. 3, shows that in composition A1 according to the invention thepolymers are dispersed evenly throughout the composition. When thePLA-PB-PLA copolymer was used in blend with PLA and PB (composition A1)at same level of total PB, the dispersion (SEM) was better than the PLAand PB blend without the copolymer as a co-continue two phasesdispersion can be seen in FIG. 5.

The impact resistance also confirmed the better dispersion with thecopolymer PLA-PB-PLA as at the same total level of PB, the presence ofthe copolymer in composition A1 allows to double the impact resistance.

1-14. (canceled)
 15. A composition comprising: a first polymer selectedfrom the group consisting of polylactic acid, starch, polybutylenesuccinate, polybutylene adipate-co-terephthalate), and mixtures thereof;a second polymer selected from the group consisting of polybutadiene,high impact polystyrene, and mixtures thereof; and a block copolymer ofpolylactic acid (PLA) and polybutadiene (PB).
 16. The compositionaccording to claim 15, wherein the block copolymer is selected from thegroup consisting of PLA-PB diblock copolymer, PLA-PB-PLA triblockcopolymer, PLA-PB multiblock copolymer, PLA-PB star copolymers, PLA-PBcomb copolymers, PLA-PB gradient containing block copolymers; andmixtures thereof.
 17. The composition according to claim 15, wherein thefirst polymer is polylactic acid.
 18. The composition according to claim15, wherein the second polymer is polybutadiene.
 19. The compositionaccording to claim 15, wherein the composition comprises from 5 to 95%by weight of the first polymer based on a total weight of thecomposition.
 20. The composition according to claim 15, wherein thecomposition comprises from 5 to 95% by weight of the second polymerbased on a total weight of the composition.
 21. The compositionaccording to claim 15, wherein the composition comprises from 1 to 90%by weight of the block copolymer based on a total weight of thecomposition.
 22. The composition according to claim 15, wherein thecomposition comprises: from 30 to 48% by weight of the first polymerbased on a total weight of the composition; from 30 to 48% by weight ofthe second polymer based on the total weight of the composition; andfrom 4 to 40% by weight of the block copolymer based on the total weightof the composition.
 23. The composition according to claim 15, whereinthe composition comprises: from 30 to 48% by weight of polylactic acidbased on a total weight of the composition; from 30 to 48% by weight ofpolybutadiene based on the total weight of the composition; and from 4to 40% by weight of the block copolymer based on the total weight of thecomposition.
 24. An article comprising the composition according toclaim
 15. 25. A process for preparing a composition comprising:contacting a first polymer with a second polymer and with a blockcopolymer of polylactic acid (PLA) and polybutadiene (PB); wherein thefirst polymer is selected from the group consisting of polylactic acid,starch, polybutylene succinate, poly(butylene adipate-co-terephthalate),and mixtures thereof; wherein the second polymer is selected from thegroup consisting of polybutadiene, high impact polystyrene, and mixturesthereof.
 26. The process according to claim 25, wherein the contactingcomprises melt blending the first polymer, the second polymer and theblock copolymer, in a single step.
 27. The process according to claim25, wherein the composition is extruded at a temperature of at least 90°C.
 28. The process according to claim 25, further comprising processingthe composition using one or more polymer processing techniques selectedfrom the group consisting of: film, sheet, pipe and fiber extrusion orcoextrusion; blow molding; injection molding; rotary molding; foaming;and thermoforming.
 29. An article formed using the process according toclaim 28.